Large Area Silicon Photomultipliers Research Articles

DarkSide-20k Veto Photon-Detector Units: construction and characterization

DarkSide-20k is a global direct dark matter search experiment situated underground at LNGS (Italy), designed to reach a total exposure of 200 tonne-years nearly free from instrumental backgrounds. The core of the detector is a dual-phase Time Projection Chamber (TPC) filled with 50 tonne of low-radioactivity liquid argon.The entire TPC wall is surrounded by a gadolinium-loaded polymethylmethacrylate (Gd-PMMA), which acts as a neutron veto, immersed in a second low-radioactivity liquid argon bath enclosed in a stainless steel vessel. The neutron veto is equipped with large-area Silicon PhotoMultiplier (SiPM) array detectors, placed on the outside of the TPC wall. SiPMs are arranged in a compact design meant to minimize the material used for PCBs, cables and connectors: the so-called Veto Photon-Detector Units (vPDUs).A vPDU comprises 16 vTiles, each containing 24 SIPMs, together with front-end electronics, and amotherboard, which distributes voltage and control signals, sums vTiles channels, and drives theelectrical signal transmission. The neutron veto will be equipped with 120 vPDUs. The paper willfocus on the production of the first vPDUs, describing the assembly chain in the U.K. institutes, inorder to underline the rigorous QA/QC procedures, up to the final characterization of the firstcompleted prototypes. Tests will be extensively performed in liquid nitrogen baths either for thesingle vTiles and for the assembled vPDUs, with the purpose of assigning a “quality passport” toeach component.

High-sensitivity low-noise photodetector using a large-area silicon photomultiplier.

The application of silicon photomultiplier (SiPM) technology for weak-light detection at a single photon level has expanded thanks to its better photon detection efficiency in comparison to a conventional photomultiplier tube (PMT). SiPMs with large detection area have recently become commercially available, enabling applications where the photon flux is low both temporarily and spatially. On the other hand, several drawbacks exist in the usage of SiPMs such as a higher dark count rate, many readout channels, slow response time, and optical crosstalk; therefore, users need to carefully consider the trade-offs. This work presents a SiPM-embedded compact large-area photon detection module. Various techniques are adopted to overcome the disadvantages of SiPMs so that it can be generally utilized as an upgrade from a PMT. A simple cooling component and recently developed optical crosstalk suppression method are adopted to reduce the noise which is more serious for larger-area SiPMs. A dedicated readout circuit increases the response frequency and reduces the number of readout channels. We favorably compare this design with a conventional PMT and obtain both higher photon detection efficiency and larger-area acceptance.

Characterisation of the MUSIC ASIC for large-area silicon photomultipliers for gamma-ray astronomy

Large-area silicon photomultipliers (SiPMs) are desired in many applications where large surfaces have to be covered. For instance, a large area SiPM has been developed by Hamamatsu Photonics in collaboration with the University of Geneva, to equip gamma-ray cameras employed in imaging atmospheric Cherenkov telescopes.The sensor being about 1 cm2, a suitable preamplification electronics has been investigated in this work, which can deal with long pulses induced by the large capacitance of the sensor. The so-called Multiple Use SiPM Integrated Circuit (MUSIC), developed by the ICCUB (University of Barcelona), is investigated as a potential front-end ASIC, suitable to cover large area photodetection planes of gamma-ray telescopes.The ASIC offers an interesting pole-zero cancellation (PZC) that allows dealing with long SiPM signals, the feature of active summation of up to 8 input channels into a single differential output and it can offer a solution for reducing power consumption compared to discrete solutions. Measurements and simulations of MUSIC coupled to two SiPMs developed by Hamamatsu are considered and the ASIC response is characterized.

Large-Area SiPM Pixels (LASiPs) in SPECT

A standard camera for Single Photon Emission Computed Tomography (SPECT) contains 50–100 photomultiplier tubes (PMTs). It is shielded by a thick layer of lead which makes it heavy and bulky. Its weight and size could be significantly reduced if replacing the PMTs by silicon photomultipliers (SiPMs). However, one would need a few thousands channels to fill a camera with SiPMs due to their small sensitive area. Alternatively, we propose to use Large-Area SiPM Pixels (LASiPs), built by summing individual currents of several SiPMs into a single output. We extended the simulation of a small camera employed with LASiPs that was presented in Guberman et al. (2021) to a large camera. The extension allowed us to study the feasibility of using larger LASiPs in a full-body SPECT camera. We found an intrinsic spatial resolution of ∼4 mm for a simulated pixel summing 25 SiPMs including SiPM noise at room temperature. Reducing the dark count rate (DCR) could improve the intrinsic spatial resolution to ∼3 mm.

SiPM module for the ACME III electron EDM search

This report shows the design and performance of a large area Silicon Photomultiplier (SiPM) module developed for the detection of fluorescent light emitted from a ∼1 liter scale volume. The module was optimized for the planned ACME III electron electric dipole moment (eEDM) search, which will be a ∼10 TeV probe for the existence of physics beyond the Standard Model of particle physics. The ACME experiment searched for the eEDM with the world’s highest sensitivity using cold ThO polar molecules (ACME II (Andreev et al., 2018 )). In ACME III, SiPMs will be used for detection of fluorescent photons (the fundamental signal of the experiment) instead of PMTs, which were used in the previous measurement. We have developed an optimized SiPM module, based on a 16-channel SiPM array. Key operational parameters are characterized, including gain and noise. The SiPM dark count rate, background light sensitivity, and optical crosstalk are found to all be well suppressed and more than sufficient for the ACME III application.

Large-Area SiPM Pixels (LASiPs) in SPECT

A standard camera for Single Photon Emission Computed Tomography (SPECT) contains 50–100 photomultiplier tubes (PMTs) that occupy at least 50% of its volume. It is shielded by a thick layer of lead which makes it heavy and bulky. Replacing PMTs by silicon photomultipliers (SiPMs) could significantly reduce the weight and size of a SPECT camera. However, the main obstacle is the limited size of SiPMs: even with the largest commercially available SiPM of 6 × 6 mm2 a few thousand channels would be needed to fill a camera. As a solution, we propose to use Large Area SiPM Pixels (LASiPs) which are built by summing the currents of several SiPMs into a single output. We developed a LASiP prototype summing 8 SiPMs using the MUSIC ASIC. To test the feasibility of using this solution in SPECT, we built a proof-of-concept micro camera that consisted of four of our LASiP prototypes coupled to a 40 × 40 × 8 mm3 NaI(Tl) crystal. We were able to reconstruct simple images of a 99m Tc capillary with an intrinsic spatial resolution of ∼2 mm and an energy resolution of ∼11.6%. We also simulated the system with Geant4, finding a good agreement with our experimental results. The simulations were extended to a larger camera, aiming to study the impact of pixel size, shape and noise.

Novel Detector Assembly for Neutron/Gamma-Ray Discrimination Applications Based on Large-Sized Scintillators Coupled to Large Area SiPM Arrays

In this work, we propose a prototype of a compact detector assembly capable of discriminating between neutrons and gamma rays, by performing pulse shape analysis. The device takes advantage of recent improvements in silicon photomultiplier (SiPM) technology and the excellent neutron/gamma-ray discrimination capabilities of new plastics and standard liquid scintillators. Our work is focused on the read-out of small-, medium-, and large-sized organic scintillators with large-area SiPM arrays ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4 \times 4$ </tex-math></inline-formula> NUV and RGB-SiPM arrays, 17 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$ </tex-math></inline-formula> 17 mm). In particular, we used EJ-276 (and its old version EJ-299) and EJ-276G plastic scintillators of several sizes (ranging from 20- to 50-mm diameter) and two large liquid scintillator cells (EJ-301 and EJ-309, 50 mm diameter <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times 50$ </tex-math></inline-formula> mm thickness). Moreover, we show the comparison of neutron/gamma-ray discrimination performance between SiPM and standard photomultiplier read-out configurations. The presented innovative device could be used in different fields, first in fundamental nuclear physics experiments, as an ancillary neutron detector for the active target at the selective production of exotic species (SPES) facility at the Legnaro National Laboratories in Italy. Additionally, it could be used in radiation monitoring applications, as a fast neutron/gamma-ray counter to be embedded in unmanned vehicles for radiation monitoring.

Performance of a 6 × 6 mm2 SiPM Module for Time-Domain Diffuse Optics

In this work we present a detector module based on large-area silicon photomultiplier, whose design has been optimized for time-domain diffuse optics measurements. In this application, to the best of our knowledge, it represents the largest area detector ever demonstrated, with expected breakthrough performance in terms of scattered light harvesting efficiency. It has been characterized using widely adopted protocols for performance assessment of instruments. We demonstrate the superior light harvesting capability and improved depth sensitivity, which can reach 4 cm. Moreover, the retrieval of optical properties has been demonstrated to be linear and with sufficient accuracy in the range corresponding to the human tissues. As a first step toward clinical application, we first performed <i>in-vivo</i> measurement at very large source-detector distances to show the suitability of the realized detector to tackle new challenges like lung or heart optical monitoring as well as imaging of deep cerebral function.

A 4π time-of-flight detector for the ND280/T2K upgrade

ND280 is a near detector of the T2K experiment which is located in the J-PARC accelerator complex in Japan. After a decade of fruitful data-taking, ND280 is scheduled for upgrade. The time-of-flight (ToF) detector, which is described in this article, is one of three new detectors that will be installed in the basket of ND280. The ToF detector has a modular structure. Each module represents an array of 20 plastic scintillator bars which are stacked in a plane of 2.4 × 2.2 m2 area. Six modules of similar construction will be assembled in a cube, thus providing an almost 4π enclosure for an active neutrino target and two TPCs. The light emitted by scintillator is absorbed by arrays of large-area silicon photo-multipliers (SiPMs) which are attached to both ends of every bar. The readout of SiPMs, shaping and analog sum of individual SiPM signals within the array are performed by a discrete circuit amplifier. An average time resolution of about 0.14 ns is achieved for a single bar when measured with cosmic muons. The detector will be installed in the basket of ND280, where it will be used to veto particle originating outside the neutrino target, improve the particle identification and provide a cosmic trigger for calibration of detectors which are enclosed inside it.

Characterization of stilbene and EJ-276 scintillators coupled with a large area SiPM array for a fast neutron dose rate detector

A 1-inch stilbene and EJ-276 (plastic) organic scintillators were characterized in view of their use in a portable survey meter for fast neutron detection and dose rate measurements in radiation protection. They were coupled with a large area Silicon Photomultiplier (SiPM) array and characterized in terms of neutron/γ–ray (n/γ) discrimination capability, count rate linearity, count rate saturation effects, temperature stability and neutron detection efficiency. A Pile-Up Rejection (PUR) algorithm was developed and tested to increase their count rate linearity with increasing dose rate. Results show that the stilbene exhibits better performance compared to the plastic in terms of: Pulse Shape Discrimination (PSD) with a Figure Of Merit (FOM) of 1.5 vs. 1.1, energy resolution (15% vs 20% at 662 keV) and fast neutron efficiency (12% vs. 9% with an AmBe source). For both scintillators, the dose rate response is linear up to 1 mSv/h with a 137Cs γ-ray source. With a neutron source, the response is linear, and the FOM is almost constant for dose rates up to 1.5 mSv/h. The PUR reduces the false neutron events by one order of magnitude when the detectors are irradiated with a γ-ray source up to 10 mSv/h, and it correctly works when irradiated with an AmBe source at 1.5 mSv/h together with a 137Cs source up to 60 μSv/h. The proposed PUR algorithm is promising but needs to be tested with a higher intensity mixed n/γ field. The temperature stability of both detectors was also studied in the temperature range from −10 °C to ＋40 °C. The light yield increases by around 25% for both detectors when reducing the temperature. The variation of the neutron count rate is around 10% in the same temperature range. This work provides a complete overview of the performance of these detectors and a coherent comparison between the two types of scintillators with the same experimental setup.

Multimodal simulation of large area silicon photomultipliers for time resolution optimization

The Silicon Photomultiplier (SiPM) sensor is replacing the extensive use of the Photomultiplier Tube (PMT) in fast timing applications. These photo-sensors can be applied in different fields such as medical imaging systems like Positron Emission Tomography (PET), LIDAR technologies or High Energy Physics (HEP) experiments. More specific, Time-of-Flight PET (ToF-PET) requires further developments to achieve a Coincidence Time Resolution (CTR) of 10ps, this enabling the real time reconstruction and in vivo molecular examination. The most recent state-of-the-art ToF-PET systems can reach 200 ps in CTR. Lowering this value will require a cross-optimization of the scintillator crystal, the sensor and the electronics at the same time. These three elements optimization will be the key to boost the timing resolution of the complete system. The aim of this work is to provide a simulation framework that enables this cross-optimization of the PET system taking into consideration the photon physics interaction in the scintillator crystal, the sensor response (size, dead area, capacitance) and the readout electronics behavior (input impedance, noise, bandwidth). This framework has allowed us to study a new promising approach that helps reducing the CTR parameter by segmenting a large area SiPM into “m” smaller SiPMs and then, summing the signals to recover all the signal spread along these smaller sensors. A 15% improvement on time resolution is expected by segmenting a 4 mm × 4 mm single sensor into 9 sensors of 1.3 mm × 1.3 mm with respect to the case where no segmentation is applied.

Evaluation of the KLauS ASIC at low temperature

The Taishan Antineutrino Observatory (TAO) is proposed to first use a cold liquid scintillator detector (−50 °C) equipped with large-area silicon photomultipliers (SiPMs) (∼10 m2) to precisely measure the reactor antineutrino spectrum with a record energy resolution of ¡ 2% at 1 MeV. The KLauS ASIC shows excellent performance at room temperature and is a potential readout solution for TAO. In this work, we report evaluations of the fifth version of the KLauS ASIC (KLauS5) from room temperature to -50 °C with inputs of injected charge or SiPMs. Our results show that KLauS5 has good performance at the tested temperatures with no significant degradation of the charge noise, charge linearity, gain uniformity or recovery time. Meanwhile, we also observe that several key parameters degrade when the chip operates in cold conditions, including the dynamic range and power consumption. However, even with this degradation, a good signal-to-noise ratio and good resolution of a single photoelectron can still be achieved for the tested SiPM with a gain of greater than 1.5 × 106 and even an area of SiPM up to 1 cm2 in one channel, corresponding to an input capacitance of approximately 5 nF. Thus, we conclude that KLauS5 can fulfill the TAO requirements for precise charge measurement.

Large-Area SiPM Pixels (LASiPs): A cost-effective solution towards compact large SPECT cameras.

Single Photon Emission Computed Tomography (SPECT) scanners based on photomultiplier tubes (PMTs) are still largely employed in the clinical environment. A standard camera for full-body SPECT employs ~50-100 PMTs of 4-8cm diameter and is shielded by a thick layer of lead, becoming a heavy and bulky system that can weight a few hundred kilograms. The volume, weight and cost of a camera can be significantly reduced if the PMTs are replaced by silicon photomultipliers (SiPMs). The main obstacle to use SiPMs in full-body SPECT is the limited size of their sensitive area. A few thousand channels would be needed to fill a camera if using the largest commercially-available SiPMs of 6×6mm2. As a solution, we propose to use Large-Area SiPM Pixels (LASiPs), built by summing individual currents of several SiPMs into a single output. We developed a LASiP prototype that has a sensitive area 8 times larger than a 6×6mm2 SiPM. We built a proof-of-concept micro-camera consisting of a 40×40×8mm3 NaI(Tl) crystal coupled to 4 LASiPs. We evaluated its performance in a central region of 15×15mm2, where we were able to reconstruct images of a 99mTc capillary with an intrinsic spatial resolution of ~2mm and an energy resolution of ~11.6% at 140keV. We used these measurements to validate Geant4 simulations of the system. This can be extended to simulate a larger camera with more and larger pixels, which could be used to optimize the implementation of LASiPs in large SPECT cameras. We provide some guidelines towards this implementation.

Probe-hosted large area silicon photomultiplier and high-throughput timing electronics for enhanced performance time-domain functional near-infrared spectroscopy.

Two main bottlenecks prevent time-domain diffuse optics instruments to reach their maximum performances, namely the limited light harvesting capability of the detection chain and the bounded data throughput of the timing electronics. In this work, for the first time to our knowledge, we overcome both those limitations using a probe-hosted large area silicon photomultiplier detector coupled to high-throughput timing electronics. The system performances were assessed based on international protocols for diffuse optical imagers showing better figures with respect to a state-of-the-art device. As a first step towards applications, proof-of-principle in-vivo brain activation measurements demonstrated superior signal-to-noise ratio as compared to current technologies.

Water-based Liquid Scintillator detector as a new technology testbed for neutrino studies in Turkey

This study investigates the deployment of a medium-scale neutrino detector near Turkey’s first nuclear power plant, the Akkuyu Nuclear Power Plant. The aim of this detector is to become a modular testbed for new technologies in the fields of new detection media and innovative photosensors. Such technologies include Water-based Liquid Scintillator (WbLS), Large Area Picosecond Photo-Detectors (LAPPDs), dichroic Winston cones, and large area silicon photomultiplier modules. The detector could be used for instantaneous monitoring of the Akkuyu Nuclear Power Plant via its antineutrino flux. In addition to its physics and technological goals, it would be an invaluable opportunity for the nuclear and particle physics community in Turkey to play a role in the development of next generation of particle detectors in the field of neutrino physics.

Development of large area Silicon Photomultipliers arrays for [formula omitted]-ray spectroscopy applications

We report on the development of custom Front-End Electronics (FEE) dedicated to large area SiPM arrays for γ-ray spectroscopy applications in high counting rate conditions. Two types of commercially available 8 × 8 arrays of 6 × 6 mm2 Silicon Photomultipliers (SiPM) and a quasi-circular array of 30 SiPM cells were coupled to dedicated Front End Electronics (FEE) boards and tested in combination with LaBr3(Ce) crystals. Energy resolution measurements were taken with standard calibration radioactive sources (60Co, 152Eu and 56Co) while the timing response was studied in comparison with industry standard photomultiplier tubes. The energy resolution measured in this setup was down to 3.09(9)% at 661 keV, while the best timing resolution measured was 222.3(22) ps. Finally, the design of a SiPM based γ-ray detector, dedicated to fast-timing applications, is presented.

Characterization of a large area silicon photomultiplier

This work illustrates and compares some methods to measure the most relevant parameters of silicon photo-multipliers (\sipm{}s), such as photon detection efficiency as a function of over-voltage and wavelength, dark count rate, optical cross-talk, afterpulse probability. For the measurement of the breakdown voltage, $V_{BD}$, several methods using the current-voltage $IV$ curve are compared, such as the "IV Model", the "relative logarithmic derivative", the "inverse logarithmic derivative", the "second logarithmic derivative", and the "third derivative" models. We also show how some of these characteristics can be quite well described by few parameters and allow, for example, to build a function of the wavelength and over-voltage describing the photodetection efficiency. This is fundamental to determine the working point of SiPMs in applications where external factors can affect it. These methods are applied to the large area monolithic hexagonal SiPM S10943-2832(X), developed in collaboration with Hamamatsu and adopted for a camera for a gamma-ray telescope, called the SST-1M. We describe the measurements of the performance at room temperature of this device. The methods used here can be applied to any other device and the physics background discussed here are quite general and valid for a large phase-space of the parameters.

Electronics method to advance the coincidence time resolution with bismuth germanate

Exploiting the moderate Cherenkov yield from 511 keV photoelectric interactions in bismuth germanate (BGO) scintillators enables one to achieve a level of coincidence time resolution (CTR) appropriate for time-of-flight positron emission tomography (TOF-PET). For this approach, owing to the low number of promptly emitted light photons, single photon time resolution (SPTR) can have a stronger influence on achievable CTR. We have previously shown readout techniques that reduce effective device capacitance of large area silicon photomultipliers (SiPMs) can yield improvements in single photon response shape that minimize the influence of electronic noise on SPTR. With these techniques, sub-100 ps FWHM SPTR can be achieved with mm2 FBK near-ultra-violet high density (NUV-HD) SiPMs. These sensors are also useful for detecting Cherenkov light due to relatively high photon detection efficiency for UV light. In this work, we measured CTR for BGO crystals coupled to FBK NUV-HD SiPMs with a passive bootstrapping readout circuit that effectively reduces the SiPM device capacitance. A range of CTR values between 200 3 and 277 7 ps FWHM were measured for 3 3 3 and 3 3 15 mm3 crystals, respectively. This readout technique provides a relatively simple approach to achieve state-of-the-art CTR performance using BGO crystals for TOF-PET.

Design and status of the Mu2e crystal calorimeter

The Mu2e experiment at Fermilab searches for the coherent neutrino-less muon to electron conversion in the Coulomb field of an aluminum nucleus. This charged-lepton flavor violating process is characterized by a distinctive signature of a mono-energetic electron (∼ 105 MeV/c) and its observation will be a clear signature of new physics beyond the Standard Model. The Mu2e goal is to improve by four orders of magnitude the search sensitivity with respect to the previous experiments. The Mu2e detector is composed of a tracker, an electromagnetic calorimeter and an external veto for cosmic rays. The calorimeter plays an important role in providing excellent particle identification capabilities, a fast online trigger filter while aiding the track reconstruction capabilities. It consists of 1348 pure CsI crystals divided in two annular disks, each one readout by two large area Silicon Photomultipliers. A large scale prototype has been tested with an electron beam, demonstrating to largely satisfy the Mu2e requirements. At the moment of writing, the crystals and SiPMs production phase is halfway through the completion. An overview of the characterization tests is reported, together with a description of the final mechanical and electronical design.

Construction and performance of the barrel electromagnetic calorimeter for the GlueX experiment

The barrel calorimeter is part of the new spectrometer installed in Hall D at Jefferson Lab for the GlueX experiment. The calorimeter was installed in 2013, commissioned in 2014 and has been operating routinely since early 2015. The detector configuration, associated Monte Carlo simulations, calibration and operational performance are described herein. The calorimeter records the time and energy deposited by charged and neutral particles created by a multi-GeV photon beam. It is constructed as a lead and scintillating-fiber calorimeter and read out with 3840 large-area silicon photomultiplier arrays. Particles impinge on the detector over a wide range of angles, from normal incidence at 90 degrees down to 11.5 degrees, which defines a geometry that is fairly unique among calorimeters. The response of the calorimeter has been measured during a running experiment and performs as expected for electromagnetic showers below 2.5 GeV. We characterize the performance of the BCAL using the energy resolution integrated over typical angular distributions for π0 and η production of σE∕E=5.2%∕E(GeV)⊕3.6% and a timing resolution of σ=150ps at 1 GeV.